snake-server

Snake server

Server for online arcade game - snake.

Game rules

The player controls the snake. The task of the game is to grow the biggest snake. In order to do this gamers can eat apples and the remains of dead snakes of other games. If the snake hits the wall, the snake will die, and the player will start again with small snake.

Client

• Python client repo: https://github.com/ivan1993spb/snake-client

Installation

Download binary from releases page: https://github.com/ivan1993spb/snake-server/releases

Also you can build server from source or pull docker image.

Install from source

With make install:

• go get -u github.com/ivan1993spb/snake-server to load source code
• cd ${GOPATH}/src/github.com/ivan1993spb/snake-server
• make build
• make install

Then:

• snake-server to start server
• Use snake-server -h to see usage information

Install from docker-hub

See docker-hub repo: https://hub.docker.com/r/ivan1993spb/snake-server

• Install docker: use fast installation script
• Choose image tag: https://hub.docker.com/r/ivan1993spb/snake-server/tags/
• Use docker pull ivan1993spb/snake-server to pull server image from docker hub
• docker run --rm --net host --name snake-server ivan1993spb/snake-server to start server
• docker run --rm ivan1993spb/snake-server -h for usage information

CLI arguments

Use snake-server -help for help info.

Arguments:

• --address - string - address to serve (default: :8080). For example: :8080, localhost:7070
• --conns-limit - int - open web-socket connections limit (default: 1000)
• --groups-limit - int - groups limit for server (default: 100)
• --log-json - bool - set this flag to use JSON log format (default: false)
• --log-level - string - set log level: panic, fatal, error, warning (warn), info or debug (default: info)
• --seed - int - random seed (default: the number of nanoseconds elapsed since January 1, 1970 UTC)
• --tls-cert - string - path to certificate file
• --tls-enable - bool - flag: enable TLS
• --tls-key - string - path to key file

API description

API methods provide JSON format.

Request POST /games

Creates game and returns JSON details.

curl -s -X POST -d limit=3 -d width=100 -d height=100 http://localhost:8080/games | jq
{
    "id": 0,
    "limit": 3,
    "width": 100,
    "height": 100
}

Request GET /games

Returns info about all games on server.

curl -s -X GET http://localhost:8080/games | jq
{
    "games": [
        {
            "id": 1,
            "limit": 10,
            "count": 0,
            "width": 100,
            "height": 100
        },
        {
            "id": 0,
            "limit": 10,
            "count": 0,
            "width": 100,
            "height": 100
        }
    ],
    "limit": 100,
    "count": 2
}

Request GET /games/{id}

Returns game information.

curl -s -X GET http://localhost:8080/games/0 | jq
{
    "id": 0,
    "limit": 10,
    "count": 0,
    "width": 100,
    "height": 100
}

Request DELETE /games/{id}

Deletes game if there is not players.

curl -s -X DELETE http://localhost:8080/games/0 | jq
{
    "id": 0
}

Request GET /capacity

Returns server capacity. Capacity is the number of opened connections divided by the number of allowed connections for server instance.

curl -s -X GET http://localhost:8080/capacity | jq
{
    "capacity": 0.02
}

Request GET /games/{id}/ws

Connects to game Web-Socket.

• Returns playground size
• Initialize game session
• Returns all objects on playground
• Creates snake
• Returns snake uuid
• Pushes game events and objects

Game Web-Socket messages description

There are input and output messages.

Output messages

Output messages - when server sends to client a data.

Output message structure:

{
    "type": output_message_type,
    "payload": output_message_payload
}

Output message can be type of:

• game - message payload contains a game events. Game events has type and payload: {"type": game_event_type, "payload": game_event_payload}. Game events contains information about creation, updation, deletion of objects on playground
• player - message payload contains a player info. Player messages has type and payload: {"type": player_message_type, "payload": player_message_payload}
• broadcast - message payload contains a group broadcast messages. Output message of type broadcast is string

Examples:

{
    "type": "player",
    "payload": ...
}
{
    "type": "game",
    "payload": ...
}
{
    "type": "broadcast",
    "payload": ...
}

Game events

Output message type: game

Game events types:

• error - payload contains string: error description
• create - payload contains game object that was created
• delete - payload contains game object that was deleted
• update - payload contains game object that was updated
• checked - payload contains game object that was checked by another game object

Examples:

{
    "type": "game",
    "payload": {
        "type": "create",
        "payload": {
            "uuid": "b065eade-101f-48ba-8b23-d8d5ded7957c",
            "dots": [[9, 9], [9, 8], [9, 7]],
            "type": "snake"
        }
    }
}
{
    "type": "game",
    "payload": {
        "type": "update",
        "payload": {
            "uuid": "a4a82fbe-a3d6-4cfa-9e2e-7d7ac1f949b1",
            "dots": [[19, 6], [19, 7], [19, 8]],
            "type": "snake"
        }
    }
}
{
    "type": "game",
    "payload": {
        "type": "checked",
        "payload": {
            "uuid": "110fd923-8167-4475-a9d5-b8cd41a60f9e",
            "dots": [[6, 17], [6, 18], [6, 19], [7, 19], [8, 19], [8, 20], [8, 21]],
            "type": "corpse"
        }
    }
}
{
    "type": "game",
    "payload": {
        "type": "update",
        "payload": {
            "uuid": "110fd923-8167-4475-a9d5-b8cd41a60f9e",
            "dots": [[6, 17], [6, 18], [6, 19], [7, 19], [8, 19], [8, 20], [8, 21]],
            "type": "corpse"
        }
    }
}

Player messages

Output message type: player

Player messages types:

• size - payload contains playground size object: {"width":10,"height":10}
• snake - payload contains string: snake identifier
• notice - payload contains string: a notification
• error - payload contains string: error description
• countdown - payload contains int: number of seconds for countdown
• objects - payload contains list of all objects on playground

Examples:

{
    "type": "player",
    "payload": {
        "type": "notice",
        "payload": "welcome to snake server!"
    }
}
{
    "type": "player",
    "payload": {
        "type": "size",
        "payload": {
            "width":255,
            "height":255
        }
    }
}
{
    "type": "player",
    "payload": {
        "type": "objects",
        "payload": [
            {
                "uuid": "e0d5c710-cdc7-43d5-9c4f-5e1e171c5207",
                "dot": [17, 18],
                "type": "apple"
            },
            {
                "uuid": "db7b856c-6f8e-4229-aee6-b90cdc575e0e",
                "dots": [[24, 24], [25, 24], [26, 24]],
                "type": "corpse"
            }
        ]
    }
}
{
    "type": "player",
    "payload": {
        "type": "countdown",
        "payload": 5
    }
}

Broadcast messages

Output message type: broadcast

Payload of output message of type broadcast contains string - a group notice that sends to all players in game group.

Example:

{
    "type": "broadcast",
    "payload": "hello world!"
}

Game primitives

Primitives that used to explain game objects:

• Direction: "north", "west", "south", "east"
• Dot: [x, y]
• Dot list: [[x, y], [x, y], [x, y], [x, y], [x, y], [x, y]]

Game objects

Game objects:

• Apple: {"type": "apple", "uuid": ... , "dot": [x, y]}
• Corpse: {"type": "corpse", "uuid": ... , "dots": [[x, y], [x, y], [x, y]]}
• Snake: {"type": "snake", "uuid": ... , "dots": [[x, y], [x, y], [x, y]]}
• Wall: {"type": "wall", "uuid": ... , "dots": [[x, y], [x, y], [x, y]]}

Objects TODO:

• Watermelon: {"type": "watermelon", "uuid": ... , "dots": [[x, y], [x, y], [x, y]]}
• Mouse: {"type": "mouse", "uuid": ... , dot: [x, y], "dir": "north"}

Input messages

Input messages - when client sends to server a game commands.

Input message structure:

{
    "type": input_message_type,
    "payload": input_message_payload
}

Input message types:

• snake - when player sends a game command in message payload to control snake
• broadcast - when player sends a short phrase or emoji to broadcast for game group

Accepted game commands:

• north
• east
• south
• west

Examples:

{
    "type": "snake",
    "payload": "north"
}
{
    "type": "snake",
    "payload": "east"
}
{
    "type": "snake",
    "payload": "south"
}
{
    "type": "snake",
    "payload": "west"
}
{
    "type": "broadcast",
    "payload": "xD"
}
{
    "type": "broadcast",
    "payload": "ok!"
}
{
    "type": "broadcast",
    "payload": "hello!"
}
{
    "type": "broadcast",
    "payload": ";)"
}

Input message size is limited: maximum 128 bytes

Game on client side

// TODO: Describe topic

License

See LICENSE.